Microsoft.Orleans.Reminders.Cosmos

Microsoft Orleans Reminders for Azure Cosmos DB

Introduction

Microsoft Orleans Reminders for Azure Cosmos DB provides persistence for Orleans reminders using Azure Cosmos DB. This allows your Orleans applications to schedule persistent reminders that will be triggered even after silo restarts or grain deactivation.

Getting Started

To use this package, install it via NuGet:

dotnet add package Microsoft.Orleans.Reminders.Cosmos

Example - Configuring Azure Cosmos DB Reminders

using Microsoft.Extensions.Hosting;
using Orleans.Configuration;
using Orleans.Hosting;

var builder = Host.CreateApplicationBuilder(args)
    .UseOrleans(siloBuilder =>
    {
        siloBuilder
            .UseLocalhostClustering()
            // Configure Azure Cosmos DB as reminder storage
            .UseCosmosDBReminders(options =>
            {
                options.AccountEndpoint = "https://YOUR_COSMOS_ENDPOINT";
                options.AccountKey = "YOUR_COSMOS_KEY";
                options.DB = "YOUR_DATABASE_NAME";
                options.CanCreateResources = true;
            });
    });

// Run the host
await builder.RunAsync();

Example - Using Reminders in a Grain

public interface IReminderGrain
{
    Task StartReminder(string reminderName);
    Task StopReminder();
}

public class ReminderGrain : Grain, IReminderGrain, IRemindable
{
    private string _reminderName = "MyReminder";

    public async Task StartReminder(string reminderName)
    {
        _reminderName = reminderName;
        
        // Register a persistent reminder
        await RegisterOrUpdateReminder(
            reminderName,
            TimeSpan.FromMinutes(2),  // Time to delay before the first tick (must be > 1 minute)
            TimeSpan.FromMinutes(5)); // Period of the reminder (must be > 1 minute)
    }

    public async Task StopReminder()
    {
        // Find and unregister the reminder
        var reminder = await GetReminder(_reminderName);
        if (reminder != null)
        {
            await UnregisterReminder(reminder);
        }
    }

    public Task ReceiveReminder(string reminderName, TickStatus status)
    {
        // This method is called when the reminder ticks
        Console.WriteLine($"Reminder {reminderName} triggered at {DateTime.UtcNow}. Status: {status}");
        return Task.CompletedTask;
    }
}

Documentation

For more comprehensive documentation, please refer to:

• Microsoft Orleans Documentation
• Reminders and Timers
• Reminder Services

Feedback & Contributing

• If you have any issues or would like to provide feedback, please open an issue on GitHub
• Join our community on Discord
• Follow the @msftorleans Twitter account for Orleans announcements
• Contributions are welcome! Please review our contribution guidelines
• This project is licensed under the MIT license